Introduction: Internet addiction is a growing globally generational, biopsychosocial, health and a bioethical problem which is still hard to determine and to describe because it's new and uncharted territory so accordingly it falls into obsessive compulsive disorder. Aim: the aim of the research is to question the frequency of internet addiction, to deepen the comprehension of the pathological Internet, questioning the quality of life and personality dimensions according to the „Great Five“ theory, and to conduct analysis to determine are there differences to the level and the type in addictions of Croatian adolescents, as well as Polish and Finnish ones; Method: the pattern in this research was made up by adolescents from Croatia, Finland and Poland. The examinees were giving their answers in writing via anonymous questionnaire on their IT classes. Conclusion: this research determined that a great number of interviewed adolescents, 86,4% of them, does not show signs of internet addiction and 12,8% of them show signs of moderate addiction. 0,8% of interviewed adolescents show signs of alarmingly serious internet addiction. Croatian adolescents statistically show a significantly bigger internet addiction (20,7%) compared to Polish adolescent (11.1%) and especially opposed to Finnish ones (5,4%).